Unwrapping Core-Shell Nanowires into Nanoribbon-based Superstructures

 

Over the last decade one-dimensional nanostructures have attracted considerable attention of the research community as promising building blocks for nanoscale devices, owing to their novel physical and chemical properties. In particular, nanoribbons (NRs) are of major interest due to their geometrical shape, comprised of a rectangular cross-section on a nanometer scale that can provide unique properties for optical, mechanical and electrical devices. Several experiments on III-V and oxide semiconductor nanoribbons have already shown promising properties, such as the wave-guiding of photons, lasing action, nonlinear polarization and high mechanical flexibility. Although these approaches have been proven to be effective, the controlled synthesis of semiconductor nanoribbons still remains a challenge.

Herein, we demonstrate a simple, and yet robust, method for the fabrication of high quality single-crystal silicon nanoribbons by the unwrapping of core/shell nanostructures. The method is based on the controlled unfurling of germanium core/silicon shell nanowires by an anisotropic plasma step, followed by etching of the sacrificial germanium core, under wet or dry conditions. Our method allows tight control over the physical and chemical properties of the fabricated nanoribbons, such as lateral and horizontal dimensions, dopant concentration control along all directions, formation of multi-layered ribbons, orthogonal chemical modification of ribbon faces etc. Lastly, the method is not only limited to the fabrication of silicon nanoribbons, but can also be easily applied to a wide range of semiconductor materials.